BAR HARBOR – Tourist dollars put Bar Harbor on the map, but the town’s largest employer is more involved with mice and molecules than visitors and vacations.

Yet the Jackson Laboratory, with an 80,000-square-foot expansion on the horizon and employment topping 1,000, is facing critical issues in common with Mount Desert Island’s other economic linchpins.

The lab and community leaders appear eager to tackle development questions before they get out of hand.

Last summer, the lab announced a five-year expansion plan, which would add considerably to the 360,000-square-foot facility tucked into the hills between Acadia National Park and the shops of downtown.

But on a larger scale, Mount Desert Island’s finite land area is at the center of a web of interrelated planning challenges. As the island’s largest institution, Jackson Lab is often blamed for unpleasant side effects of growth – traffic congestion, ruined Acadia National Park vistas, a lack of day care services and a shortage of affordable housing.

“You’re always bumping up against something here,” said Millard Dority, vice chairman of the Bar Harbor Planning Board. “If it’s not the Atlantic Ocean, it’s Acadia National Park.”

Dority is quick to add: “It would be a very sad thing to ever see it go. … Think about how important that lab is, how lucky we are to have it.”

The lab’s evolving role will be the focus of a meeting tonight by the Bar Harbor Conservation Commission, and its chairman, Gary Friedmann, said one of the key questions is how major developments like the lab and its expansion factor into what people want the town to be.

“Frankly, there are people in town who are saying that they don’t want the lab to be growing at this rate forever,” Friedmann said. “With the boom in biotechnology, there is no end in sight.”

No official policy on research facilities is written into the town’s comprehensive plan. But Bar Harbor has always worked cooperatively with Jackson Lab, which provides just the sort of year-round jobs necessary to stabilize the fickle tourism industry.

In fact, Town Manager Dana Reed credited the lab’s growth when announcing a recent upgrade in the town’s credit rating.

The 73-year-old lab is Bar Harbor’s biggest employer, with 1,176 people on staff and 200 additional jobs anticipated when the current expansion is complete. Only five years ago, the lab employed just over 500 people. And with $47.6 million in federal funds awarded annually, the possibilities for the lab are considerable.

“We’re maxed out right now,” Lee Wilbur, chief operating officer for Jackson Lab, said Friday. “We’re utilizing all the lab space we have.”

No one can say how large the facility may become. Expansion of the physical plant is dictated by the total research dollars the lab earns for its work on cancer, heart disease, Alzheimer’s and dozens of other human ailments. The lab’s continued success guarantees its growth.

“Mouse genetics has become the linchpin of biomedical research,” lab spokeswoman Joyce Peterson said. “Our funding has doubled over the last five years and shows no signs of abating.”

In recent years, the lab has started expanding off Mount Desert Island, founding a West Coast research facility at the University of California at Davis and an employee training center in Fairfield.

The satellite facilities provide support, but the lab has no plans to move the heart of its operation out of Hancock County, Wilbur said. The Bar Harbor campus includes 147.5 acres, most of which remain undeveloped. And the lab’s creative work thrives on daily interaction between the scientists.

“Even with the expansions, we’ll still be able to operate in an environment where everyone knows each other,” Wilbur said. “We still have land and space here. We haven’t pushed the envelope on that point.”

Dority said that he, as a town planner, has never considered telling Jackson Lab how large it could grow. But at some point, he expects, the town will have to address the pressure it puts on town infrastructure.

“We know it’s affecting the town. There’s no way a [large] business like that wouldn’t have an impact,” he said.

Zoning restrictions such as building dimensions and parking requirements have traditionally been used to indirectly limit growth in Bar Harbor. But if the town also hopes to combat sprawl in large developments such as the Jackson Laboratory campus, the planning board may have to take more creative approaches, Dority said.

Jackson Laboratory was granted its own land use zone, so changing its development requirements would not directly affect any other business or landowner, he said.

In December, lab representatives outlined a five-year plan to the board, admitting that this round of construction may bump up against some zoning regulations. They offered to work with the town to find nontraditional solutions.

For instance, the lab may not be able to supply the requisite parking space for each of its employees. But a combination of staggered work shifts and mass transit programs has the potential to meet the lab’s actual parking needs and reduce traffic on Mount Desert Island’s roads to boot, Wilbur said.

Due in part to the housing shortage, a substantial minority of the lab’s employees live on the mainland, commuting from eight counties. Three buses are already transporting a number of these workers, and the lab may be interested in working with Downeast Transportation, Island Explorer, or even a ferry service to expand its mass transit system, Wilbur said.

It all depends on cooperation, he said.

“We feel very much a part of Bar Harbor,” Wilbur said. “We’re trying to get more proactive. We’re trying to find a way to disseminate information to everybody. I think it’s only fair for the people to understand what’s happening.”

The lab has been open with town planners, and has worked with the town to address shared problems in the past. Bar Harbor, too, is looking to joint action, Dority said.

“It’s an obligation and a responsibility of the planning board to look for solutions to these problems,” he said. “There’s not a person on that board who wouldn’t say, ‘Let’s talk about it.'”

The conservation commission will discuss Jackson Laboratory’s evolving role at 7 p.m. Monday, Jan. 14, in the Bar Harbor Municipal Building.